Exercise ball



FIG. 1 is a front perspective view of an exercise ball.

FIG. 2 is a front view thereof.

FIG. 3 is a rear view thereof.

FIGS. 4 and 5 are opposing side views thereof.

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The broken line showing of portions of the exercise ball depicts environment and forms no part of the claim. 

CLAIM The ornamental design for an exercise ball, as shown and described. 